Wave packet molecular dynamics simulations of hydrogen under extreme conditions

With the aid of “Wave Packet Molecular Dynamics” (WPMD) simulations we investigate hydrogen under extreme conditions. In this model the protons are treated as classical point-particles, whereas the electrons are represented by antisymmetrized wavepackets following a pseudo-hamiltonian dynamics. For the simulations we use 512 particles in a periodically continued cubic box. The equation of state, i.e. the pressure p as function of the temperature T for an electron density n=2×1029 m−3 is rather flat around 12,000 K. In this regime the molecules dissociate. The linear mixing model shows at lower absolute values a more pronounced behaviour of the pressure. The new path integral Monte Carlo results for T>10,000 K show a similar flattening, while the tight-binding model shows hardly any. A comparison of our WPMD results with experiments for p(n) at T=300 K shows the importance of antisymmetrization.